DMH-induced rat colon cancer is being studied as a model for human colorectal malignancy. Neither the primary tumor nor subcutaneous transplant generations of it metastasize frequently to the liver. Recent studies show that portal venous injection of a tumor cell suspension produce numerous foci of hepatic metastatic disease. Work continues on efforts to isolate and develop a RIA for the identified colon tumor-specific factor. Results of studies comparing surgical resection of the primary tumor with intralesional BCG-CW injection of it failed to show a salutary effect of immunotherapy.